The use of shoes by humans dates back to the rudimentary employment of materials from nature such as woven vegetal fibers and, later on, animal leather. Currently, it can be said that for almost any activity or occasion there exists a shoe specifically designed to meet the particular needs thereof.
For instance, the use of sandals, espadrilles, slippers, huaraches (leather sandals), diving slippers etc. is customary for leisure, rest, beach and diving activities. These shoes are characterized by their constant contact with water, their light weight and their being open to promote foot ventilation, with the exception of diving slippers that are usually closed, i.e. they cover the toes and part of or the entire instep.
Nevertheless, an issue with this type of shoes is that they constantly suffer from water, sand, stones, mud and other foreign objects going into them; this in turn is uncomfortable for the wearer's foot and, in many cases, generates foul odors due to the buildup of decomposable organic matter and, therefore, render the shoes highly unhygienic and promote the growth of fungi. For example, it is frequent when people return from the beach or camps that shoes give off unpleasant smells once they are taken out from luggage due to the accumulation of organic matter and elevated humidity inside the shoe, which promotes the incidence of fungi. In diving slippers, the removal of foreign objects inside them is particularly difficult and the wearer needs to wash them out several times to take away as much of these objects as possible, yet without achieving a 100% removal thereof.
In the prior art there exist some insoles aimed at increasing ventilation and decreasing humidity inside the shoe. For instance, in U.S. Pat. No. 5,809,665 an insole is disclosed that is characterized by ventilation holes at the lower surface thereof and intercommunicated to each other. However, it is obvious that these holes can be penetrated by foreign objects when stepping on; furthermore, said holes are not interconnected with the rest of the insole, i.e. there is no connection of the holes with the entire surface of the insole and therefore ventilation is poor at those areas of the foot not immediately above the holes.
In the same manner, U.S. Pat. No. 5,979,076 can be cited, which discloses a ventilated shoe that includes ventilating holes on the shoe sole. However, these holes do not reach out or intercommunicate in all directions inside the shoe; therefore, it would prove difficult to remove foreign objects inside the shoe through these holes.
From the above, prior-art shoes have insoles incorporated therein with the purpose of promoting a better ventilation inside the shoe. Nevertheless, should foreign objects exist inside the same such as sand, mud or other small-sized items, it may prove difficult to remove these from the shoe; in addition, the draining function has not been satisfactorily met to date.
As explained above, leisure and beach shoes need a quick removal of water in order to prevent foreign matter from accumulating and therefore generate foul odors and poor hygienic conditions. In a nutshell, the issue lies in that an insole be designed such that the wearer has little to worry about the constant cleaning of the interior of the shoe.